Articular Cartilage Flashcards
What are the major 3 components of articular cartilage?
water, collagen, proteoglycans
How does the water in cartilage help to create resistance to loading?
frictional resistance of water to flow by small pore size within the ECM creates a pressurization of the fluid (highly resistant to compressive loading)
What type of collagen do you find in joints and what is its purpose?
major type is type II and it provides tensile and shear strength and immobilizes proteoglycans
Name the 3 major types of glycosaminoglycan chains in cartilage.
chondroitin sulfate
keratan sulfate
dermatan sulfate
Does cartilage buffer quick movements or long standing compression better?
when moving quickly the water cannot move quickly enough to change the shape of the cartilage and so cartilage is better suited for withstanding constant, longstanding compression
Describe the special purpose of the surface, middle/deep and calcified zones of cartilage.
surface: glides and resists shear and control fluid flows
middle/deep: accept compressive loads, produce matrix
calcified zone: anchored to bone
What is the structure of the superficial zone?
collagen fibrils are arranged parallel to surface
chondrocytes elongate along axis of surface
low proteoglycan content and high H2O content
What is the structure of the middle zone?
disorganized arrangement, spheroid chondrocytes
low H2O, higher proteoglycan content
What is the structure of the deep zone?
spheroid columns of chondrocytes which are vertically oriented, extending into the tidemark
lowest H2O content
______ synthesize and assemble the ECM components and direct ECM remodeling.
Chondrocytes synthesize and assemble the ECM components and direct ECM remodeling.
balance between synthesis and wear varies with age, young people have the greatest reserve
How does cartilage change over time?
GAG predominance changes from chondroitin-4 sulfate to chondroitin-6 sulfate
total chondroitin concentration falls and keratin sulfate increases
aggregation is diminished with advancing age
What is necessary in articular cartilage injury to get some degree of wound healing response?
must cross the tidemark into vascular subcentral bone, begets invasion of the defect with undifferentiated cells and a repair response
repair tissue- fibrocartilage is different in composition, structure and material properties than articular cartilage
What are therapeutic options for treatment of cartilage injury?
microfracture
auto or allograft plug
cell based therapies (structure is difficult to develop)
What are the symptoms of osteoarthritis?
joint pain, restriction of motion, crepitus, joint effusions and deformity (is actually arthritis no arthritis)
large due to degeneration of cartilage and then joint surfaces
What are the signs of osteoarthritis? (radiographic)
focal joint space narrowing, osteophyte formation, subchondral sclerosis, subcentral cyst formation, deformity
(inflammatory arthritis: symmetric joint space narrowing, periarticular erosions, periarticular osteopenia, joint subluxation, osteophytes rare)
